1. Field
The presently disclosed subject matter relates to vehicle suspension systems, and in particular to trailing arm configurations for vehicle suspension systems and methods for manufacturing such a suspension system.
2. Description of the Related Art
Vehicle suspension systems can include a complicated set of linkages, pneumatic devices, and springs that aim to provide a smooth ride for a vehicle. For example, a four bar linkage suspension includes a knuckle connected to lower and upper control arms which in turn are connected to the frame of a vehicle. The control arms are rotatably connected to the vehicle frame (e.g., by a “bar” type pivot/connecting device) so that an end can rotate and move substantially vertically with respect to the vehicle frame. A knuckle typically connects each of the lower control arms to a respective upper control arm, and a wheel mount structure can be attached to the knuckle. Thus, the wheel, when mounted, is permitted to move in a vertical direction relative to the vehicle frame. A stabilizer bar can be connected between the left and right side control arms such that when a particular vertical movement occurs in a wheel on one side of the vehicle, a corresponding movement can take place in the corresponding wheel on the other side of the vehicle. This action prevents roll of the vehicle during turning and/or maneuvering over rough/bumpy roadway surfaces.
A spring is typically connected from one of the upper or lower control arms or knuckle to the vehicle frame, and a strut or shock absorber is also connected between the respective control arm or knuckle and vehicle frame. Thus, the vertical movement of the wheel can be controlled and damped to provide a relatively smooth ride for the vehicle.
Although the above-described four bar suspension system is a common type of vehicle suspension system, there are other types of vehicle suspension systems. Another common vehicle suspension system is the two bar suspension system. In one example of a two bar suspension system, a lower control arm is pivotally connected to a vehicle frame. A lower portion of a knuckle can be connected to the lower control arm and an upper portion of the knuckle can be connected to a rotary link member that incorporates a spring and shock absorber system. Thus, the upper control arm is not necessary in this case.
Typical vehicle suspension systems often require a great number of attachment mechanisms, and a great deal of space. The high number of components and their complex shapes also add cost and weight to a vehicle. In addition, the large volume required for these components also creates restrictions in design and also creates problems during repair in terms of added time required for repair due to limited access to components, and added cost due to this added repair time and due to multiple part requirements. The restriction on design due to the large volume taken by the suspension system can also result in diminished passenger space and/or reduced door space for the vehicle, especially with regard to rear suspension systems and rear doors.
In particular, existing rear vehicle suspensions include both single and double trailing arm configurations. As shown in FIG. 8, a conventional double trailing arm suspension structure includes a first upper trailing arm 94 and a first lower trailing arm 99 which extend in the front/rear direction of the vehicle between the knuckle or wheel connection structure 91 and the vehicle body 97. A second upper arm 95 extends in a right/left lateral direction with respect to the vehicle and is located under the upper trailing arm 94. A second lower arm 92 and third lower arm 93 are connected via respective bearings with the wheel connection structure 91 and extend in a right/left lateral direction with respect to the vehicle. The second lower arm 92 and third lower arm 93 are located above a point of attachment between the first lower trailing arm 99 and the wheel connection structure 91. In this particular system, a damper 98 is connected to the wheel connection structure 91.
Single trailing arm configurations are also known. For example, FIG. 6 shows, in schematic form, a conventional pivot point CP for connecting a single arm to a vehicle frame in a single arm type suspension system. In this case, the conventional pivot point CP is located vertically lower and horizontally more forward than connection pivot points 11AP and 12AP of the dual arm system depicted in FIG. 1. Several drawbacks are associated with single trailing arm configurations. For example, because connection pivot point CP is located in a far forward position relative to the vehicle's longitudinal axis, the mounting thereof is limited by frame construction requirements. Thus, the amount of anti-squat (mechanical compliance) provided by a single arm suspension system may be reduced. In addition, the far forward position of pivot point CP can interfere with the rear door entry, requiring either a smaller door entryway which may interfere with entry and exit capability for second or third row passengers (depending on type of vehicle) or reduction in efficiency of the suspension system to compensate for a larger doorway. In addition, the single trailing arm configuration is often configured from a single stamped material, which has limited strength capability as compared to a tubular trailing arm.
There is a longstanding need in the art to address the above-described issues, features and characteristics. The disclosed subject matter is directed to a vehicle suspension system that can include a dual trailing arm configuration. As shown in FIG. 6, the dual trailing arm configuration allows the vehicle suspension system to act as if it were a single trailing arm system in which the single trailing arm is connected to the vehicle frame at pivot point IP (which is located in the door opening of the vehicle). However, the actual connection between the upper and lower trailing arms and the vehicle frame of the disclosed dual trailing arm suspension are located at pivot points 11AP and 12AP, which are spaced from the door opening of the vehicle. Thus, the suspension system can provide better rear door access for passengers while possibly providing a better ride characteristic. The dual arms allow the wheel to rotate about a virtual arm structure with pivot point IP. The length of the virtual arm (virtual swing arm length) can be longer than a length of an actual single swing arm.